Electronically controlled electric motors are coming more and more to the fore in a number of areas of application. In this connection electric motors are involved in which the required periodic switching of coils is no longer performed by a commutator, but rather by electronic switching devices. The electronic switching devices can include for example suitable sensors which determine when the stator and the rotor for the coils about to be switched, are in a position relative to each other that is favorable to or requires switching. It is understood that the electronic switching devices must also ensure that current is fed to the respective coils in the appropriate direction.
It is also known to use permanent magnets either for the stator poles or for the rotor poles in electronically controlled electric motors. Permanent magnets offer a number of advantages, such as no current consumption, small dimensions, and simple manufacturing and assembly. Such electric motors are used today in many technical areas, such as, for example, also in the automobile industry as drive motors for radiator fans or servo-devices. The available space for installing an electrically operated fan for cooling the radiator is very limited, particularly in automobiles in which the combustion motor is installed lengthwise in the travel direction. Conventional permanent magnet motors cannot be used because of their large axial structural length.
European Patent Publication EP 0,645,542 discloses an automobile cooling fan with an electric (EC) motor wherein the windings of the armature and other electronic components are connected with a printed circuit on a carrier or support. In that case, connecting the free ends of the windings with the printed circuit is still relatively complicated and costly.
U.S. Pat. No. 5,548,458 discloses a circuit arrangement for connecting the stator windings of a brushless, electronically commutated electric motor that is provided for driving computer hard disc drives. That disclosure shows concentrically arranged conductor paths on a side of an annular disk-shaped support plate that faces away from the stator assembly.
The ends and/or the leads of the winding wires are fastened by means of solder pads on the support plate, whereby the solder pads are connected by connecting conductors with the current paths.
Furthermore, the European Patent Publication EP 0 777 312 A2 discloses a stator for electric motors that comprises a stator assembly, stator windings, and a circuit configuration for the stator windings arranged on an endface of the stator assembly. The circuit configuration particularly has an insulating part with groove-shaped chambers for receiving electrical connection leads that are insulated relative to each other for connecting the winding ends of the stator windings. The publication does not, however, disclose a star connection with a star point.